Show interfaces Gi3/1

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Jan 28th, 2009
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When requesting "show interfaces Gi3/1" on my MLS i get the following output:

GigabitEthernet3/1 is up, line protocol is up (connected)

Hardware is C6k 1000Mb 802.3, address is 000f.f89b.4c0a (bia 000f.f89b.4c0a)

Internet address is

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s, media type is LH

input flow-control is off, output flow-control is on

Clock mode is auto

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:01, output 00:00:01, output hang never

Last clearing of "show interface" counters 22w3d

Input queue: 0/75/0/768 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

Does the Queueing strategy as well as the Output Queue refer to the "Software Queue" or "Hardware Queue"???

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Joseph W. Doherty Wed, 01/28/2009 - 10:40
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I believe it should be IOS managed software queues.

Elly Bornstein Wed, 01/28/2009 - 15:13
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on a L3 interface on all MLS switches, input and output queues refer to software queues, or packets going to the CPU.

This queue is FIFO, but does take high priority packets into account.

Luis Melendrez Wed, 01/28/2009 - 15:20
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Is there any way I can check my hardware queue (TxQ)?? if they are congested or not? or what % is being used?

According to some books I have read, there exist a hardware queue and a software queue but dont know how to check each of this queues with some "show commands"

Elly Bornstein Wed, 01/28/2009 - 15:28
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What kind of switch is this? 6500? is qos enabled?

Elly Bornstein Wed, 01/28/2009 - 18:42
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With QoS disabled you basically have a FIFO queue that is tail dropping all traffic it does not have buffer space for. If you run out of buffer spaces on a non-virtual interface, they will appear as output drops.

show interface | i drops|line

With QoS enabled you can actually look into drops per hardware queue with:

'show queueing interface gx/y'

6500 is a hardware forwarding platform, packets are switched too fast to be able to monitor queue fullness, which is why you will almost always see 0/2000/0/0 (on a L2 interface) where the first 0 is packets in queue. So drops is really the only indication of congestion.


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